1. Field of the Invention
The present invention relates to an exposure device, and in particular, to an exposure device which exposes a photosensitive material with a light beam modulated by a space modulation element or the like in accordance with image information.
2. Description of the Related Art
Conventionally, various types of exposure devices, in which exposing is carried out with a light beam modulated by using a space modulation element such as a digital micro-mirror device (DMD) or the like in accordance with image data (image information), are proposed.
For example, the DMD is a mirror device in which many mirrors whose reflecting surface angle can be changed in accordance with control signal are arranged on a semiconductor substrate such as a silicon substrate or the like in two dimensional manner. A exposure device using the DMD has a light source, a (first) lens system, the DMD and a (second) lens system. The light source irradiates a laser light. The first lens system collimates the light beam irradiated from the light source. The DMD is disposed in a substantially focusing position of the first lens system. The light beam reflected at the DMD is image-formed by the second lens system on a scanning surface. The light beam is modulated by on-off controlling of each of the micro-mirrors of the DMD by the control signal generated in accordance with the image data or the like. Image exposure is carried out by the modulated laser light.
Such exposure device is used, for example, for exposing a photo resist which is used when manufacturing a printed wiring plate. As the result, many advantages are obtained such that cost for manufacturing and managing a photomask is reduced, a time required for trial manufacturing of a printed wiring board becomes shorter, change of design or the like of a circuit can be carried out easily and speedy, and the like. Recently, a build up wiring plate has been developed in order to respond to requirement for high density packaging. Using of the above mentioned exposure device when manufacturing the build up wiring plate has been investigated.
However, when manufacturing of the build up wiring board, an electric circuit (a wiring pattern) is formed on a surface of a build up layer laminated on a core substrate by an alignment mark (an inner via, a pattern, a pad or the like) provided at the core substrate (an inner layer substrate) being as a reference. Accordingly, the exposure device has a problem in an alignment (identification of the alignment mark and positioning (aligning) of an exposure pattern) which is carried out after the build up layer is laminated on the core substrate.
For example, such as a scanning type drawing equipment described in a Japanese Patent Laid-Open No. 2000-275863, when a pattern is recorded on a laminated material of a print wiring board or the like by means of a conventional device which directly exposes (records image) on a photo resist in a mask-less manner, an alignment mark such as a through hole or the like is detected by an image-pickuping device with a visible light, and a wiring patter formed on each layer is positioned (aligned). However, it is difficult to identify the alignment mark on the core substrate after building up (laminating) of the build up layer by such image-pickuping device using a visible light when manufacturing the build up wiring board. Therefore, establishment of alignment technology becomes a problem in a case of to using an exposure device which exposes a pattern (an image) with light beam when manufacturing the build up wiring board.
On the other hand, by that an alignment mark is masked by a tape before plating and the tape is stripped (removed) after plating thereby the alignment mark can be visually identified in order to enable to identify the alignment mark, identification may be carried out by using the image-pickuping device mentioned above or the like. However, manufacturing processes cannot be automated by the method mentioned above, merit to introduce the device fades, and there is a problem that a manufacture cost has risen.